Datasets Activity Stream About Submit Order by Relevance Name Ascending Name Descending Last Modified Popular Go 1 dataset found Licenses: Open Government Licence 3.0 (United Kingdom) Formats: GeoJSON HTML Themes: Mapping Towns & cities Tags: diffusion Filter Results Air Quality - Diffusion Tubes Tubes measure nitrogen dioxide levels at their location. Used to identify any pockets of air pollution and provide indication of exposure levels. HTML Esri REST GeoJSON CSV KML ZIP